Method and system for delaying shift and throttle commands based on engine speed in a marine vessel

ABSTRACT

A method for delaying shift and throttle commands based on engine speed comprises establishing a predetermined threshold engine speed. Shift and throttle commands are calculated based on the position of a control lever which allows an operator to manually control shift and throttle functions. Execution of the shift and throttle commands is delayed if the engine speed is above the predetermined maximum threshold engine speed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of provisional application No.61/173,946 filed in the United States Patent and Trademark Office onApr. 29, 2009, the full disclosure of which is incorporated herein byreference and priority to which is claimed pursuant to 35 U.S.C. section120.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to electronic shift and throttle systemsand, in particular, to delaying shift and throttle functions based onengine speed.

2. Description of the Related Art

Vehicles such as marine vessels are often provided with electronic shiftand throttle systems. These systems typically allow an operator tocontrol the shift and throttle functions of a propulsion unit using acontrol lever which is pivotally mounted on a control head. The controllever is moveable between a forward wide open throttle (forward WOT)position and a reverse wide open throttle (reverse WOT) position,through a neutral position. A controller reads the position of thecontrol lever as the control lever moves through its operational range.The controller sends shift commands and throttle commands which drive ashift actuator and a throttle actuator based on the position of thecontrol lever.

For example, U.S. Pat. No. 7,330,782 issued on Feb. 12, 2008 to Grahamet al. and the full disclosure of which is incorporated herein byreference, discloses an electronic shift and throttle system in which aposition sensor is used to sense the position of a control lever. Theposition sensor is electrically connected to an electronic control unit(ECU) and sends an electrical signal to the ECU. The ECU is able todetermine the position of the control lever based on the voltage levelof the electrical signal received from the position sensor. The ECU thendetermines the positions to which the output shafts of the shiftactuator and the throttle actuator should be set.

Each of the output shafts is also coupled to a corresponding positionsensor. Electrical signals sent by these position sensors may be used todetermine the positions of the output shafts. This feedback may be usedto govern the ECU. This is beneficial because variances and play betweencomponents used to link throttle actuators to throttles make itdesirable to calibrate throttle controls. Calibrated throttle controlsallow an operator to delay shift and throttle functions based on enginespeed in a marine vessel.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved methodand system for delaying shift and throttle commands based on enginespeed in a marine vessel.

There is accordingly provided a method for delaying shift and throttlecommands based on engine speed. The method comprises establishing apredetermined threshold engine speed. Shift and throttle commands arecalculated based on the position of a control lever which allows anoperator to manually control shift and throttle functions. Execution ofthe shift and throttle commands is delayed if the engine speed is abovethe predetermined maximum threshold engine speed.

In a preferred embodiment, a first threshold engine speed and a secondengine threshold speed are established. The first threshold engine speedis greater than the second engine threshold speed. For example, thefirst threshold engine speed may be 1,500 RPM while the second thresholdengine speed may be 800 RPM. The throttle actuator is moved to an idleposition to decrease the engine speed until the engine speed falls belowthe first threshold engine speed. The shift actuator is moved to aneutral position after the engine speed falls below the firstpredetermined threshold engine speed. Execution of the throttle commandis delayed until after the shift actuator is moved to the neutralposition. Execution of the shift command is delayed until after theexecution of the throttle command and the engine speed rises above thesecond predetermined threshold engine speed.

Also provided is an electronic shift and throttle system for delayingshift and throttle commands based on the speed of an engine. The systemcomprises a sensor for sensing the speed of the engine. There is a shiftfor shifting between a forward gear and a reverse gear, through aneutral gear. There is also a throttle actuator for moving a throttlebetween an idle position and a wide open throttle position. A controlhead includes a pivotable control lever for manually controlling shiftand throttle functions of the engines. The control lever is moveablethrough a range of positions. An engine control unit calculates a shiftcommand and throttle command based on a position of the control lever.An engine servo module delays execution of the shift command if thespeed of the engine is above a first predetermined threshold enginespeed. In particular, the engine servo module commands the throttleactuator to move the throttle to the idle position to decrease enginespeed and delays execution of the shift command until after the enginespeed falls below the first threshold engine speed.

In a preferred embodiment, the engine servo module commands the throttleactuator to move the throttle actuator towards the wide open positionthrottle position, to increase the engine speed, after the engine speedfalls below the first predetermined threshold speed. The engine servomodule also commands the shift actuator to shift to the neutral gearafter engine speed falls below the first predetermined threshold enginespeed. The engine servo module the delays the execution of the throttlecommand until after the shift actuator shifts to neutral the neutralgear. The engine servo module delays execution of the shift commanduntil the engine speed rises above a second predetermined thresholdengine speed.

The present invention provides an improved method for delaying shift andthrottle commands based on engine speed that allows an operator toquickly shift from forward high throttle to reverse high throttle orvice versa without overstressing the gear box and while helping toprevent the engine from stalling under the high opposite force of thepropeller.

BRIEF DESCRIPTIONS OF DRAWINGS

The invention will be more readily understood from the followingdescription of the embodiments thereof given, by way of example only,with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a marine vessel provided with aplurality of propulsion units and an improved electronic shift andthrottle system;

FIG. 2 is a side view of an engine of one of the propulsion units ofFIG. 1;

FIG. 3 is a top view of the a control head of the marine vessel of FIG.1;

FIG. 4 is a schematic diagram illustrating the electronic shift andthrottle system of FIG. 1;

FIG. 5 is an elevation view of the control head of FIG. 3 illustratingan operational range of a control lever thereof;

FIG. 6 is a table illustrating the lighting of indicator or gear lampsas the control lever of FIG. 5 is moved through the operational range;

FIG. 7 is side elevation view of a shift actuator of the propulsion unitof FIG. 2 illustrating an operational range of an actuator arm thereof;

FIG. 8 is a side elevation view of a throttle actuator of the propulsionunit of FIG. 2 illustrating an operational range of an actuator armthereof;

FIG. 9 is a side elevation view of the throttle actuator of FIG. 8illustrating a second side thereof;

FIG. 10 is a perspective view of the throttle actuator of FIG. 8illustrating the first side thereof;

FIG. 11 is a perspective view of the throttle actuator of FIG. 8illustrating the second side thereof;

FIG. 12 is a sectional view taken along line A-A of FIG. 11;

FIG. 13 is a fragmentary side view, partially in section and partlyschematic, of the throttle actuator of FIG. 8, a throttle, and a linkagetherebetween;

FIG. 14 is a sectional view of the throttle of FIG. 13 illustrating thethrottle in an idle position;

FIG. 15 is a sectional view of throttle of FIG. 13 illustrating thethrottle in a wide open throttle (WOT) position;

FIG. 16 is a sectional view of throttle of FIG. 13 illustrating movementof the throttle as the throttle controls are being calibrating;

FIG. 17 is a flow chart illustrating the logic of a throttle calibrationmethod disclosed herein;

FIG. 18 is a schematic diagram illustrating the delay of shift andthrottle functions; and

FIG. 19 is set of tables illustrating the delay of shift and throttlefunctions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings and first to FIG. 1, this shows a marinevessel 10 which is provided with a plurality of propulsion units in theform of three outboard engines 12 a, 12 b and 12 c. However, in otherexamples, the marine vessel 10 may be provided with any suitable numberof inboard and/or outboard engines. It is common to see two engines andpractically up to five engines in pleasure marine vessels. The marinevessel 10 is also provided with a control head station 14 that supportsa control head 16. The control head 16 is provided with a microprocessor(not shown).

A first one of the engines, namely the port engine 12 a, is best shownin FIG. 2. The port side engine 12 a includes a shift actuator 18 a, athrottle actuator 20 a, and an electronic servo module (ESM) 22 a; allof which are disposed within a cowling 24. Second and third ones of theengines, namely the center engine 12 b and starboard 12 c engine, havesubstantially the same structure as the port engine 12 a and areaccordingly not described in detail herein.

The control head 16 is best shown in FIG. 3. The control head 16includes a housing 26. A port control lever 30 and starboard controllever 40 are each pivotally mounted on the housing 26. The port controllever 30 normally controls the shift and throttle functions of the portengine 12 a but, in this example, also controls the shift and throttlefunctions of the center engine 12 b both of which are shown in FIG. 1.The starboard control lever 40 controls the shift and throttle functionsof the starboard engine 12 c which is also shown in FIG. 1. In a marinevessel with five engines, the port control lever would control the shiftand throttle functions of the port, center port and center engines whilethe starboard control lever would control the shift and throttlefunctions of the starboard engine and starboard center engine.

The port control lever 30 is provided with a master trim switch 50 whichallows an operator to simultaneously trim all of the engines. The portand starboard engines are trimmed individually using a respective porttrim button 31 and starboard trim button 41, which are both disposed onthe housing 26. The center engine 12 b is under the control of a centertrim button 31 (not shown).

The housing 26 also supports a plurality of indicator or gear lampswhich, in this example, are LED lamps. A port forward indicator 32, portneutral indicator 34, and port reverse indicator 36 are disposed on aside of housing 26 adjacent the port control lever 30. A starboardforward indicator 42, starboard neutral indicator 44, and a starboardreverse indicator 46 are disposed on a side of housing 26 adjacent thestarboard control lever 40. A port neutral input means 38 and starboardneutral input means 48 are also disposed on the housing 26. An RPM inputmeans 52, synchronization (SYNC) input means 54, and SYNC indicator lamp56 are also all disposed on the housing 26. In this example, the portneutral input means 38, starboard neutral input means 48, RPM inputmeans 52, and SYNC input means 54 are buttons but any suitable inputdevices may be used.

As best shown in FIG. 4, the control head 16 and the engines 12 a, 12 band 12 c, together with their corresponding shift actuators 18 a, 18 band 18 c; throttle actuators 20 a, 20 b and 20 c; and ESMs 22 a, 22 band 22 c, form part of an electronic shift and throttle system 60. Theelectronic shift and throttle system 60 further includes a gateway 62and a plurality of engine management modules (EMMs) 64 a, 64 b and 64 c.Each EMM is associated with a corresponding ESM. The control head,gateway, ESMs, and EMMs communicate with each other over a private CANnetwork 66. The electronic shift and throttle system 60 is designed tosupport two control heads and control up to five engines. Components ofoptional fourth and fifth engines 12 d and 12 e as well as an optionalsecond control head 17 are shown in ghost.

A single master ignition switch 68 provides power to the entire privateCAN network 66. However, start and stop functions are achieved byindividual switches 70 read by the control head 16 as discrete inputs orserial data. Any command an operator inputs to the control head 16 tostart, stop, trim, shift or accelerate one of the engines 12 a, 12 b or12 c is sent to the corresponding ESM 22 a, 22 b or 22 c andcorresponding EMM 64 a, 64 b or 64 c over the CAN network 66. The ESMsand EMMs are each provided with a microprocessor (not shown). In thisexample, a private network cable 72 that carries the CAN lines from thecontrol head 16 to the engines 12 a, 12 b and 12 c has two separatewires used to shut down the engines in the event that the CAN network 66fails.

Information from the electronic shift and throttle system 60 is madeavailable to devices on a NMEA2K public network 74 through the gateway62. The gateway 62 isolates the electronic shift and throttle system 60from public messages, but transfers engine data to displays and gauges(not shown) on the public network 74. The gateway 62 is also providedwith a plurality of analog inputs 76 which may be used to read andbroadcast fuel senders or oil senders or other resistive type senderssuch as rudder senders or trim tab senders on the public network 74.

Referring now to FIG. 5, the port side 30 control lever is moveablebetween a forward wide open throttle (forward WOT) position and areverse wide open throttle (reverse WOT) position, through a neutralposition. An operator is able to control the shift and throttlefunctions of the port engine 12 a by moving the port control lever 30through its operational range. The port control lever 30 is alsoprovided with a forward detent, neutral detent, and reverse detent alldisposed between the forward WOT position and reverse WOT position. Thisallows the operator to physically detect when the port control lever 30has moved into a new shift/throttle position. As shown in FIG. 6, theport forward indicator 32, port neutral indicator 34, and port reverseindicator 36 light up to reflect the position of the port control lever30 shown in FIG. 5.

Referring back to FIGS. 4 and 5, the microprocessor supported by thecontrol head 16 reads the position of the port control lever 30 andsends shift and throttle commands to the ESM 22 a via the private CANnetwork 66. The ESM 22 a commands the shift actuator 18 a and throttleactuator 20 a which are best shown in FIGS. 7 and 8, respectively. FIG.7 shows that the shift actuator 18 a has an actuator arm 19 a which ismoveable between a forward position and a reverse position with aneutral position therebetween. FIG. 8 shows that the throttle actuator20 a has an actuator arm 21 a which is moveable between an idle positionand a wide open throttle (WOT) position. An actuator position sensor142, shown in FIG. 12, signals the actuator position to the ESM 22 ashown in FIG. 4. This feedback may be used to govern the control head16. The shift and throttle functions of the port side engine 12 a arethereby controlled.

It will be understood by a person skilled in the art that the shift andthrottle functions of the starboard engine 12 c are controlled in asimilar manner using the starboard control lever 40 shown in FIG. 2. Theshift and throttle functions of the center engine 12 b are under thecontrol of the port control lever 30 in this example. Accordingly, asthus far described, the electronic shift and throttle system 60 isconventional.

However, the electronic shift and throttle control system 60 disclosedherein is provided with an improved shift actuator 18 a and throttleactuator 20 a as shown in Figures actuators as shown in FIGS. 7 and 8respectively. The shift and throttle actuators are both rotary actuatorswhich have substantially the same structure and function insubstantially the same manner, with the exception of the actuator arm 19a or 21 a. This will be understood by person skilled in the art.Accordingly, only the throttle actuator 20 a is described in detailherein.

Referring to FIGS. 7 through 11, the throttle actuator 20 a of the portengine 12 a is shown in greater detail. The throttle actuator 20 agenerally includes a waterproof housing 112 which encases variouscomponents, a motor 114 extending from and bolted to the housing 112,and a harness 116 for electrically connecting the throttle actuator 20 ato the electronic shift and throttle system 60. The housing 112 isprovided with a plurality of mounting holes 118 a, 118 b, 118 c, and 118d allowing the throttle actuator 112 to be mounted as needed. In thisexample, the housing 112 also includes a body 120 and a cover 121 boltedthe body 120. Removing the cover 121 provides access to the variouscomponents encased in the housing 112. The motor 114 may be rotated ineither a first rotational direction or a second rotational directionopposite to the first direction depending on the direction of theelectric current supplied to the motor 114. As best shown in FIG. 11,the harness 16 is wired to the motor 114 and supplies an electriccurrent thereto.

Referring now to FIG. 12, the housing 112 encases a worm gear 122 whichis coupled to an output shaft (not shown) of the motor 114. The wormgear 122 engages a worm wheel 124 which is integrated with a spur gearpinion 126. The worm gear 122 imparts rotary motion to both the wormwheel 124 and spur gear pinion 126. The spur gear pinion 126 impartsrotary motion to a sector spur gear 128 which is integrated with anoutput shaft 130 of the throttle actuator 20 a. The output shaft 130 isthereby rotated by the motor 114. Bearings 132 a and 132 b are providedbetween the output shaft 130 and the housing 112 to allow free rotationof the output shaft 130 within the housing 112. A sealing member in theform of an O-ring 134 is provided about the output shaft 130 to seal thehousing.

As best shown in FIG. 11, the distal end 136 of the output shaft 130 issplined. There is a longitudinal, female threaded aperture 138 extendinginto the output shaft 130 from the distal end 136 thereof. The aperture138 is designed to receive a bolt to couple the output shaft 130 to theactuator arm 21 a as shown in FIG. 8. Referring back to FIG. 12, thereis a magnet 140 disposed at a proximal end 141 of the output shaft 130.There is also a position sensor 142 which senses a position of themagnet 140 as the output shaft 130 rotates. The position sensor 142 isthereby able to determine the rotating position of the output shaft 142.In this example, the position sensor 142 is a Hall Effect sensor but inother embodiments the sensor may be a magnetoresistive position sensoror another suitable magnetic rotational sensor. The position sensor 142is mounted on a circuit board 144 which is mounted on the throttleactuator housing 112. More specifically, in this example, the circuitboard 144 is mounted on the housing cover 121. As best shown in FIGS. 9and 10, the circuit board 144 is wired to the harness 116 allowing theposition sensor 142 to send an electrical signal to the ESM 22 a whichis shown in FIG. 4.

As best shown in FIG. 13, the actuator arm 21 a is coupled to a throttle150 of the port engine 12 a, shown in FIG. 2, by a throttle linkage 152.The throttle 150 includes a throttle body 154 and a throttle plate 156mounted on a rotatable throttle shaft 158. There is also a throttleposition sensor (TPS) 159 mounted on top of the throttle shaft 158 whichsenses the position of the throttle shaft as it rotates. In thisexample, the TPS 159 is a potentiometer and communicates with the EMM 64a shown in FIG. 4. Together the plate 156, the shaft 158 and the TPS 159form a butterfly valve member which is spring loaded to a closedposition shown in FIG. 14. Referring back to FIG. 13, rotation of theactuator output shaft 130 drives the actuator arm 21 a to rotate thethrottle shaft 158. Rotation of the throttle shaft 158 causes thethrottle 150 to move between an idle position shown in FIG. 14 and a WOTposition shown in FIG. 15. Whether the throttle 150 is in the idleposition or WOT position is dependent on the rotational position ofoutput shaft 130. The throttle actuator 20 a is an external actuator,the electronic shift and throttle system 60 may be installed as a kit onan existing engine.

To correlate position of the throttle 150 with the position of theactuator arm 21 a, it is necessary calibrate the throttle controls ofthe electronic shift and throttle system 60. Once calibrated, the idleposition of the actuator arm 21 a will correspond to the idle positionof the throttle 150.

The ESM 22 a, shown in FIG. 4, calibrates the throttle controls by usingthe voltage level sent by the TPS 159, the duty cycle of the electricalsignal sent by the actuator position sensor 142 and the amount ofcurrent flowing into the actuator motor 114. The voltage level of TPS159 varies with the position of the throttle plate 156. In this example,the voltage level of TPS 159 is low when the throttle plate 156 isperpendicular and in contact with throttle housing 154, as shown in FIG.14, and the voltage level of the TPS 159 is high when the throttle plate156 is parallel with throttle housing 154 as shown in FIG. 15. The dutycycle of the electrical signal sent by the actuator position sensor 142varies with the position of the throttle actuator arm 21 a. In thisexample and as shown in FIG. 13, the duty cycle of position sensor 142is low when the actuator arm 21 a at the idle position and is high whenthe actuator arm 21 a is at the WOT position. The amount of currentflowing into the actuator motor 114 is low when the actuator arm 21 amoves freely and increases when the throttle plate 156 is in contactwith the throttle housing 154 thereby stalling the motor 114.

The ESM 22 a calibrates the throttle controls by determining thethrottle position where the TPS voltage is the lowest, while avoidingresidual tension in the throttle linkage 152. This is done by 20 openingthe throttle 150 and moving it back to the idle position in increments.This is best shown in ghost in FIG. 16. The ESM 22 a controls theopening of the throttle 150 and moves the throttle 150 back to the idleposition. In this example, the throttle 150 is moved back in incrementsof 1° towards a hard stop, i.e. where the throttle plate 156 comes intocontact with the throttle housing 154. At each increment the ESM 22 acommunicates 25 with the EMM 64 a and requests the voltage level of theTPS 159 shown in FIG. 13. The ESM 22 a stores the value. This isrepeated until the throttle plate 156 comes to the hard stop. The ESM 22a determines if the throttle 150 is at the hard stop by measuring thecurrent flowing in the actuator motor 114. The ESM 22 a assumes that thethrottle 150 is at the hard stop if the current is above apre-determined value. The ESM 22 a then establishes the idle position asbeing where the lowest valid voltage level that is at least a minimaldistance away from hard stop was measured. The minimal distance from thehard stop ensures that the tension created in the throttle linkage 152while moving the throttle plate 156 against the hard stop is released.In this example, the minimal distance is defined in degrees and set to0.75°. However, the minimal distance may range for example between 0.3°and 1.5°.

In this example, the calibration procedure will terminate successfullyif the following parameters are met:

-   1. The voltage level of the signal from the throttle position sensor    has changed more than the movement amount while calibrating (in this    example 0.2V). This amount confirms the actuator actually moved the    throttle plate.-   2. The minimum expected idle position voltage level (in this example    0.3V)<=the voltage level of the signal from the throttle position    sensor in the idle position<=the maximum expected idle position    voltage level (in this example 0.62V).    The values may vary in other embodiments.

FIG. 17 best shows the above described calibration procedure. The newcalibration position is stored in EEPROM if the calibration procedureterminates successfully. A similar calibration procedure is used for thecenter and starboard engines.

Referring back to FIG. 3, once the calibration procedure is completed,the operator can more accurately increase or decrease engine throttle bymoving the port control lever 30 through its operational range. Theoperator can also shift gears by moving the port control lever 30through its operational range. The control head 16 sends shift andthrottle commands to the ESM 64 a which is shown in FIG. 4. The ESM 64 athen commands the shift actuator 18 a and the throttle 20 a actuator ofthe port engine 12 a. However, the ESM 64 a will not command the shiftactuator 20 a to shift gears if the engine speed is above apredetermined maximum threshold speed, even if the ESM 64 a is commandedto do so by the control head 16. In this example, the predeterminedmaximum threshold speed is 1,500 RPM. Instead the ESM 64 a will commandthe throttle actuator 18 a to move to the idle position in order tolower the engine speed. The ESM 64 a will also command the throttleactuator 18 a to move to the idle position when an actual gear of theport engine 12 a is not the same as a commanded gear.

FIG. 18 shows a method for delaying shift commands 212 and throttlecommands 214 for the port engine 12 a. A position sensor 33, that ispart of the control head 16, reads the position of the port controllever 30. The control head 16 sends shift and throttle commands 212 and214 to the ESM 64 a of the port engine 12 a over the CAN network 66. Theshift and throttle commands 212 and 214 are based on the position of theport control lever 30. The ESM 64 a commands the shift actuator 18 a andthrottle actuators 20 a of the port engine 12 a. The port engine 12 a isalso provided with a speed sensor 13 a. The speed sensor 13 a signalsthe engine speed to the EMM 22 a. The EMM 22 a communicates the enginespeed 216 to the ESM 64 a over the CAN network 66. The ESM 64 a willdelay commanding the shift actuator 18 a to shift gears if the enginespeed is above the predetermined maximum threshold speed of 1,500 RPM.Meanwhile, the ESM 64 a will command the throttle actuator 18 a to moveto the idle position. This eventually causes the engine speed to dropbelow 1,500 RPM. The ESM 64 a then commands the shift and throttleactuators 18 a and 20 a in accordance with the shift and throttlecommands 212 and 214 received from the control head 16. To preventstalling, the ESM 64 a will not command the shift actuator 20 a to shiftgears unless the engine speed 216 is above a predetermined minimumthreshold speed. In this example, the predetermined minimum thresholdspeed is 800 RPM. However, in other examples, the minimum thresholdvalue may be in the range of 500 RPM to 1100 RPM.

FIG. 19 is a graphical representation which shows delaying shift andthrottle commands based on engine speed. The following is a descriptionof the steps illustrated.

STEP 0—The control lever is in a forward position, the engine is inforward gear, and the engine speed is above the predetermined maximumthreshold speed.STEP 1—The operator quickly moves the control lever from the forwardposition to a reverse position. The ESM commands the throttle actuatorto move the throttle to the idle positionSTEP 2—The throttle is kept at the idle position to allow the enginespeed to drop.STEP 3—The ESM waits until the engine speed drops below thepredetermined maximum threshold speed before commanding the shiftactuator to shift to neutral.STEP 4—The ESM commands the shift actuator to shift into neutral afterthe engine speed drops below the predetermined maximum threshold speed(T1).STEP 5—The ESM applies the throttle command after the shift actuatorshifts into neutral. This causes the engine speed to increase.STEP 6—The ESM applies the shift command after the engine speed risesabove the predetermined minimum threshold speed (T2). This prevents theengine from stalling.STEP 7—The ESM commands the shift actuator to shift into reverse.

Accordingly, and with reference to FIG. 4, if the operator quickly movesthe control lever 30 from the forward WOT position to the reverse WOTposition, the ESM 64 a will not command the shift actuator 18 a to shiftgears until the engine speed drops below 1,500 RPM. The same logicapplies when the control lever is moved from a reverse position to aforward position.

The method and system for delaying shift and throttle commands based onengine speed disclosed herein allows an operator to quickly shift fromforward high throttle to reverse high throttle or vice versa withoutoverstressing the gear box and while helping to prevent the engine fromstalling under the high opposite force of a propeller.

It will be understood by a person skilled in the art that the method andsystem for delaying shift and throttle commands based on engine speeddisclosed herein may be implemented in any electronic shift and throttlecontrol system, regardless of whether the vehicle is a marine vessel.

It will further be understood by a person skilled in the art that manyof the details provided above are by way of example only, and are notintended to limit the scope of the invention which is to be determinedwith reference to following claims.

1. A method for delaying shift and throttle commands based on enginespeed in an electronic shift and throttle system, the method comprisingthe steps of: establishing a first threshold engine speed; determining aposition of a control lever which allows an operator to manually controlshift and throttle functions; calculating a shift command based on theposition of the control lever and calculating a throttle command basedon the position of the control lever; delaying execution of the shiftcommand by a shift actuator if the engine speed is above the firstthreshold engine speed; and delaying execution of the throttle commandby a throttle actuator if the engine speed is above the first thresholdengine speed.
 2. The method as claimed in claim 1 wherein the step ofdelaying execution of the throttle command includes: moving the throttleactuator to an idle position to decrease the engine speed; and delayingexecution of the throttle command until after the engine speed fallsbelow the first predetermined threshold engine speed.
 3. The method asclaimed in claim 2 further including the step of moving the shiftactuator to a neutral position prior to execution of the throttlecommand.
 4. The method as claimed in claim 3 wherein the step of movingthe shift actuator to the neutral position includes moving the shiftactuator to the neutral position after the engine speed falls below thefirst predetermined threshold engine speed.
 5. The method as claimed inclaim 1 further including the step of establishing a second thresholdengine speed and wherein the step of delaying execution of the shiftcommand includes: moving the throttle actuator to an idle position todecrease the engine speed; moving the shift actuator to a neutralposition after the engine speed falls below the first predeterminedthreshold engine speed; executing the throttle command to increase theengine speed after the shift actuator is moved to the neutral position;and delaying the execution of the shift command until after the enginespeed rises above the second predetermined threshold engine speed. 6.The method as claimed in claim 1 wherein the step of establishing thefirst threshold engine speed includes establishing the first thresholdengine speed at 1,500 RPM.
 7. The method as claimed in claim 5 whereinthe step of establishing the second threshold engine speed includesestablishing the second threshold engine speed between 500 RPM and 1100RPM.
 8. The method as claimed in claim 5 wherein the step ofestablishing the second threshold engine speed includes establishing thesecond threshold engine speed at an engine speed lower than the firstthreshold engine speed.
 9. A method for delaying shift and throttlecommands based on engine speed in an electronic shift and throttlesystem, the method comprising the steps of: establishing a firstthreshold engine speed and a second engine threshold speed; determininga position of a control lever which allows an operator to manuallycontrol shift and throttle functions; calculating a shift command basedon the position of the control lever and calculating a throttle commandbased on the position of the control lever; moving the throttle actuatorto an idle position to decrease the engine speed until the engine speedfalls below the first threshold engine speed; moving the shift actuatorto a neutral position after the engine speed falls below the firstpredetermined threshold engine speed; delaying the execution of thethrottle command until after the shift actuator is moved to the neutralposition; and delaying the execution of the shift command until afterthe execution of the throttle command and the engine speed rises abovethe second predetermined threshold engine speed.
 10. The method asclaimed in claim 9 further wherein the step of establishing the firstthreshold engine speed includes establishing the first threshold enginespeed at 1,500 RPM.
 11. The method as claimed in claim 9 further whereinthe step of establishing the second threshold engine speed includesestablishing the second threshold engine speed at between 500 RPM and1100 RPM.
 12. The method as claimed in claim 9 wherein the step ofestablishing the second threshold engine speed includes establishing thesecond threshold engine speed at an engine speed lower than the firstthreshold engine speed.
 13. A method for delaying shift and throttlecommands based on engine speed in an electronic shift and throttlesystem, the method comprising the steps of: establishing a firstthreshold engine speed at 1,500 RPM and a second engine threshold speedat between 500 RPM and 1100 RPM; determining a position of a controllever which allows an operator to manually control shift and throttlefunctions; calculating a shift command based on the position of thecontrol lever and calculating a throttle command based on the positionof the control lever; moving the throttle actuator to an idle positionto decrease the engine speed until the engine speed falls below thefirst threshold engine speed; moving the shift actuator to a neutralposition after the engine speed falls below the first predeterminedthreshold engine speed; delaying the execution of the throttle commanduntil after the shift actuator is moved to the neutral position; anddelaying the execution of the shift command until after the execution ofthe throttle command and the engine speed rises above the secondpredetermined threshold engine speed.
 14. A method for delaying shiftcommands when gears are changed in an electronic shift and throttlesystem based on engine speed, the method comprising the steps of:establishing a first threshold engine speed and a second thresholdengine speed; determining a position of a control lever which allows anoperator to manually control shift; calculating a shift command based onthe position of the control lever; moving the throttle actuator to anidle position to decrease the engine speed until the engine speed fallsbelow the first threshold engine speed; moving the throttle actuator toan open position to increase the engine speed after the engine speedfalls below the first predetermined threshold engine speed; delaying theexecution of the shift command until the execution of the throttlecommand and the engine speed rises above the second predeterminedthreshold engine speed.
 15. The method as claimed in claim 14 furtherwherein the step of establishing the first threshold engine speedincludes establishing the first threshold engine speed at 1,500 RPM. 16.The method as claimed in claim 14 further wherein the step ofestablishing the second threshold engine speed includes establishing thesecond threshold engine speed at 500 RPM and 1100 RPM.
 17. The method asclaimed in claim 14 wherein the step of establishing the secondthreshold engine speed includes establishing the second threshold enginespeed at an engine speed lower than the first threshold engine speed.18. An electronic shift and throttle system for delaying shift andthrottle commands based on the speed of an engine, the systemcomprising: a sensor for sensing the speed of the engine; a shiftactuator for shifting between a forward gear and a reverse gear througha neutral gear; a throttle actuator for moving a throttle between anidle position and a wide open throttle position; a control headincluding a pivotable control lever for manually controlling shift andthrottle functions of the engine, the control lever being moveablethrough a range of positions; an engine control unit for calculating ashift command and a throttle command based on a position of the controllever; an engine servo module for delaying execution of the shiftcommand if the speed of the engine is above a first predeterminedthreshold engine speed, the engine servo module commanding the throttleactuator to move the throttle to the idle position to decrease enginespeed and the engine servo module delaying execution of the shiftcommand until after the engine speed falls below the first predeterminedthreshold engine speed.
 19. The system as claimed in claim 18 whereinthe engine servo module commands the throttle actuator to move thethrottle actuator towards the wide open throttle position to increasethe engine speed after the engine speed falls below the firstpredetermined threshold speed, and the engine servo module delayingexecution of the shift command until the engine speed rises above asecond predetermined threshold engine speed.
 20. The system as claimedin claim 18 where in the engine servo module commands the shift actuatorto shift to the neutral gear after the engine speed falls below thefirst predetermined threshold engine speed, and the engine servo modulethe delaying execution of the throttle command until after the shiftactuator shifts to the neutral gear.